Look
here (although I suspect it was written by a drunken marketing person who had overheard one end of an engineer's phone conversation).
Protection is typically triggered by such things as:
* output offset voltage
* high temperature
* overdriven outputs
* power on/off delay
* protection system error
* phase of the moon
It looks like this fault is not uncommon. Looking at the descriptions, I would not be surprised if one of the last 2 are not involved (and probably not the last one).
Because people report it to be sensitive to orientation, I would first go looking for dry joints, cracks in boards, loose connections, and stuff like this. See if gently flexing the board in different places with an eraser tipped pencil to see if there's any sensitivity to movement.
The second thing to look for is an open or shorted output or driver transistor, since this will cause an output offset problem that would be detected almost immediately on output (and are possibly the most likely failures).
